Here are some sample answers to your questions:
1. In my last role as project manager, I led a team of 5 people from different departments to launch a new product. We had to work closely together to develop the product, create marketing materials, and launch on time. I held weekly standup meetings, delegated tasks based on strengths, and created accountability by having individuals report progress. We launched ahead of schedule thanks to great teamwork.
2. Recently I took on a big project individually outside of work hours. I redesigned my company's website on my own over 6 months. It was challenging learning new coding skills and getting the design right. I persevered through many revisions and launched the new site to great reviews.